Buffer.hs

-- |
-- Copyright:   (c) 2022 Andrew Lelechenko
-- Licence:     BSD3
-- Maintainer:  Andrew Lelechenko <andrew.lelechenko@gmail.com>
--
-- 'Buffer' for strict 'Text', based on linear types.
module Data.Text.Builder.Linear.Buffer (
  Buffer,
  runBuffer,
  runBufferBS,
  dupBuffer,
  consumeBuffer,
  eraseBuffer,
  foldlIntoBuffer,
  (|>),
  (|>.),
  (|>#),
  (<|),
  (.<|),
  (<|#),
  (><),
  (|>$),
  ($<|),
  (|>%),
  (%<|),
  (|>&),
  (&<|),
  (|>…),
  (…<|),
) where

import Data.Text.Array qualified as A
import Data.Text.Internal (Text (..))
import GHC.Exts (Addr#, Int (..), Ptr (..), cstringLength#, setByteArray#)
import GHC.ST (ST (..))

import Data.Text.Builder.Linear.Char
import Data.Text.Builder.Linear.Core
import Data.Text.Builder.Linear.Dec
import Data.Text.Builder.Linear.Double
import Data.Text.Builder.Linear.Hex

-- | Append 'Text' suffix to a 'Buffer' by mutating it.
-- If a suffix is statically known, consider using '(|>#)' for optimal performance.
--
-- >>> :set -XOverloadedStrings -XLinearTypes
-- >>> runBuffer (\b -> b |> "foo" |> "bar")
-- "foobar"
(|>) ∷ Buffer ⊸ Text → Buffer

infixl 6 |>
buffer |> (Text src srcOff srcLen) =
  appendExact
    srcLen
    (\dst dstOff → A.copyI srcLen dst dstOff src srcOff)
    buffer

-- | Prepend 'Text' prefix to a 'Buffer' by mutating it.
-- If a prefix is statically known, consider using '(<|#)' for optimal performance.
--
-- >>> :set -XOverloadedStrings -XLinearTypes
-- >>> runBuffer (\b -> "foo" <| "bar" <| b)
-- "foobar"
(<|) ∷ Text → Buffer ⊸ Buffer

infixr 6 <|
Text src srcOff srcLen <| buffer =
  prependExact
    srcLen
    (\dst dstOff → A.copyI srcLen dst dstOff src srcOff)
    buffer

-- | Append a null-terminated UTF-8 string
-- to a 'Buffer' by mutating it. E. g.,
--
-- >>> :set -XOverloadedStrings -XLinearTypes -XMagicHash
-- >>> runBuffer (\b -> b |># "foo"# |># "bar"#)
-- "foobar"
--
-- The literal string must not contain zero bytes @\\0@ and must be a valid UTF-8,
-- these conditions are not checked.
--
-- Note the inconsistency in naming: unfortunately, GHC parser does not allow for @#<|@.
(|>#) ∷ Buffer ⊸ Addr# → Buffer

infixl 6 |>#
buffer |># addr# =
  appendExact
    srcLen
    (\dst dstOff → A.copyFromPointer dst dstOff (Ptr addr#) srcLen)
    buffer
  where
    srcLen = I# (cstringLength# addr#)

-- | Prepend a null-terminated UTF-8 string
-- to a 'Buffer' by mutating it. E. g.,
--
-- >>> :set -XOverloadedStrings -XLinearTypes -XMagicHash
-- >>> runBuffer (\b -> "foo"# <|# "bar"# <|# b)
-- "foobar"
--
-- The literal string must not contain zero bytes @\\0@ and must be a valid UTF-8,
-- these conditions are not checked.
(<|#) ∷ Addr# → Buffer ⊸ Buffer

infixr 6 <|#
addr# <|# buffer =
  prependExact
    srcLen
    (\dst dstOff → A.copyFromPointer dst dstOff (Ptr addr#) srcLen)
    buffer
  where
    srcLen = I# (cstringLength# addr#)

-- | Append given number of spaces.
(|>…) ∷ Buffer ⊸ Word → Buffer

infixr 6 |>…
buf |>… 0 = buf
buffer |>… (fromIntegral → spaces@(I# spaces#)) =
  appendExact
    spaces
    ( \(A.MutableByteArray dst#) (I# dstOff#) →
        ST
          ( \s# →
              (# setByteArray# dst# dstOff# spaces# 32# s#, () #)
          )
    )
    buffer

-- | Prepend given number of spaces.
(…<|) ∷ Word → Buffer ⊸ Buffer

infixr 6 …<|
0 …<| buf = buf
(fromIntegral → spaces@(I# spaces#)) …<| buffer =
  prependExact
    spaces
    ( \(A.MutableByteArray dst#) (I# dstOff#) →
        ST
          ( \s# →
              (# setByteArray# dst# dstOff# spaces# 32# s#, () #)
          )
    )
    buffer

-- | This is just a normal 'Data.List.foldl'', but with a linear arrow
-- and unlifted accumulator.
foldlIntoBuffer ∷ ∀ a. (Buffer ⊸ a → Buffer) → Buffer ⊸ [a] → Buffer
foldlIntoBuffer f = go
  where
    go ∷ Buffer ⊸ [a] → Buffer
    go !acc [] = acc
    go !acc (x : xs) = go (f acc x) xs